Prepare the crust; butter a nine-inch tart pan with a removable bottom; set aside.

Place flour, pecans, confectioners' sugar, espresso powder & salt in a food processor. Pulse about three times, just to combine. Use a fork to toss in cold butter cubes. Pulse until butter pieces are the size of oatmeal flakes and peas (they do not need to be uniform, you're aiming coarsely cut bits). Slowly add the egg yolk, pulsing briefly after each addition. When egg is completely in, process dough in long pulses (about 10 seconds each) until the dough forms clumps and curds (the processor will make a noticeable change in sound when this happens). Try not to overprocess. Turn dough out onto a work surface and, very gently, knead until any remaining dry bits are incorporated.

Press dough evenly onto the bottom and up the sides of prepare tart pan. Place crust in freezer for at least 30 minutes. (freezing the crust will allow you to bake it without the use of pie weights.)

Preheat oven to 375 F.

Butter/spray the shiny side of a piece of foil and fit foil, butter side down, tightly over frozen tart crust. Place crust on a baking sheet and bake 25 minutes. Carefully remove foil and, using the back of a spoon, gently press down on any puffy areas. Return uncovered crust to oven and bake for another 8-10 minutes, or until crust is a deep golden brown. Remove crust from oven and place onto a cooling rack. Cool completely before filling with dulce de leche. (recipe below)

Dulce de leche filling; prepare a double boiler; fill a medium saucepan with about 1-inch of water and bring the water to a slow simmer. Find a large heatproof bowl that fits snugly over the saucepan (make sure the bottom of the bowl does not touch simmering water). Pour both cans of sweet milk into heatproof bowl and place the bowl over simmering water. Stirring occasionally, cook until the sweet milk thickens and turns golden brown. This can take up to three-four hours; replenish the simmering water as needed. The sweet milk will thin out a bit before morphing into gorgeous dulce de leche - it's a long process but well worth the wait. {Note; if you have a faster method, feel free to use it.}

Remove the bowl of dulce de leche from the heat and set aside until cool to room temperature. It will thicken up even more whilst cooling.

When dulce de leche has come to room temperature, scrape it into cool tart crust. Use an offset spatula to spread it out into an even layer. {Note; use a light hand when spreading so you don't disturb the fragile crust.} Place tart in refrigerator for about 30 minutes to firm up.

Prepare whiskey whipped cream; place cream and salt into stand mixer bowl fitted with whisk attachment. Beat on med-high until soft peaks are just beginning to form. With mixer set to medium speed, start adding whiskey and sugar. Turn speed up to med-high and beat until stiff peaks form (do not overbeat).

Remove tart from fridge and scrape whipped cream on top of filling. Dust with sifted ground cinnamon, if desired

I have seen dulce de leche at a small handful of specialty stores, but I like making things from scratch. The more work that goes into a recipe, the more I feel as though I've earned the right to enjoy it (and ask other people to do the dishes!). :D You can use pre-made dulce de leche in this recipe; I'd recommend about 2 jars.

Really nice job with this. The espresso is going to help so much in balancing the super sweetness of the dulce. Just curious-the short cut trick of baking the cans in a bain marie- just doesn't appeal to you?

I know that's an easier method, but it makes me nervous. There's simply too much that could go wrong; my imagination cannot handle it. (I don't like being in the same room as someone who is opening a champagne bottle or a tube of biscuit dough.) :D Please feel free to use the method you're comfortable with, I know they're a few floating around. xoxo